Hello, Any St.Aubins in Montreal, Past or Present?

I am looking for the birthplace of my great grandfather Francois/Francis St.Aubin born 1814/15.I have been researching all eight of his siblings and their families for a clue as to his birthplace.The U.S. censuses just report birthplace Canada/French.Finally, one son's death certificate stated, Francis birthplace was Montreal. Canada.The 1850 Lucas County, Ohio census reported Georges St.Aubin 80 yrs old, born ib France living with the Francis St.Aubin family.I suspect Georges to be Francis father?there was also a possible brother, Anthony St.Aubin, about the same age, living in Lucas County.